OTIS speed-volume data exploratory analysis
Chi-Hyun Kim
Last updated 2026-02-22
Spatial coverage
Mapping out points where speed (brown points) and volume (green points) were measured year by year, we see that the measurement locations are quite different between years but very similar (though not identical) between speed/volume measurements in a given year.
Temporal coverage
Upshot: Measurement dates vary systematically from year to year. This includes the months covered, the share of weekdays/weekends covered, as well as the share of weekends by month.
The temporal distribution of speed data is quite similar to volume data but not exactly the same.
Coverage of data through the hours of the day is even (i.e., for each measurement instance there is one row for each hour).
Speed
Volume
Speeding descriptives
Characteristics of measurement locations
Joining the 2022-2025 speed measurement data spatially to Philadelphia street centerlines, we get this coverage:
There are a few measurement points at highways and highway ramps. We exclude them for all analyses below.
The distribution of speed measurement points by roadway type is thus:
| Roadway type | N | Percent |
|---|---|---|
| Major Arterial | 230.00 | 41.97% |
| Minor Arterial | 166.00 | 30.29% |
| Collector | 132.00 | 24.09% |
| Local | 20.00 | 3.65% |
Speeding by time of day
Overall
Binary
Detailed
By roadway type
Binary
Detailed
Off-peak speed corridors
Where are the roadways where the prevalence of speeding at off-peak hours is the highest?
Any speeding
The table below shows roadway type distribution for segments where more than half of traffic speeds in off-peak hours.
| Distribution of roadway types with more than half of traffic speeding in off-peak hours | ||
| Roadway type | N | Percent |
|---|---|---|
| Major Arterial | 76.00 | 54.68% |
| Minor Arterial | 37.00 | 26.62% |
| Collector | 24.00 | 17.27% |
| Local | 2.00 | 1.44% |
| Percentage of measurement points with more than half of traffic speeding in off-peak hours, by roadway type | |
| Roadway type | Percent |
|---|---|
| Major Arterial | 33.04% |
| Minor Arterial | 22.29% |
| Collector | 18.18% |
| Local | 10.00% |
Major arterials and high speed ramps are disproportionately prone to speeding drivers in off-peak hours.
The map below shows the location of these majority-speeding roadways.
High speeding
The table below shows roadway type distribution for segments where more than 10% of traffic speeds 11mph or more over the limit in off-peak hours.
| Distribution of roadway types with more than 10% of traffic speeding by more than 11mph in off-peak hours | ||
| Roadway type | N | Percent |
|---|---|---|
| Major Arterial | 53.00 | 66.25% |
| Minor Arterial | 19.00 | 23.75% |
| Collector | 6.00 | 7.50% |
| Local | 2.00 | 2.50% |
| Percentage of measurement points with more than 10% of traffic speeding by more than 11mph in off-peak hours, by roadway type | |
| Roadway type | Percent |
|---|---|
| Major Arterial | 23.04% |
| Minor Arterial | 11.45% |
| Collector | 4.55% |
| Local | 10.00% |
Major arterials and high speed ramps are even more disproportionately prone to high-speeding drivers in off-peak hours.
The map below shows the location of these high-speeding roadways.
Relationship between volume and speeding
Are drivers more likely to speed for a given roadway type if overall volume is lower?
Any speeding
There doesn’t seem to be any definitive pattern.
High speeding
There doesn’t seem to be any definitive pattern.
